The present invention is in the general field of metallurgy and relates particularly to non-ferrous metallurgy. The invention is especially related to aluminum or aluminum alloys.
It has been previously discovered, U.S. Pat. No. 2,793,949, that inorganic substances may be incorporated in metals to produce a composite material product. It is taught therein that mixtures of molten metals, including aluminum, and a large variety of inert fillers, including alumina, may be smelted together if the non-metallic material to be incorporated into the metal is wetted by the molten metal used. The wetting agents chosen are those among substances which are capable of lowering the surface tension between the metals and the materials to be incorporated therein. Such prior art also teaches that to modify the structural properties of a metal only slight amounts, less than 1 percent, say 0.1 percent, of powders or crystal materials should be added to the metal. On the other hand, when the object is to obtain, for example, abrasive compositions, the ratio of hard materials to be mixed with the molten metal should preferably exceed 50 percent by volume of the composite product and may be as high as 95 percent. Although a wide variety of metals and fillers are disclosed, no commercial success has apparently been achieved with the use of any compositions prepared by such process. Also, a number of the compositions disclosed in the reference are highly dangerous, being in fact explosive compositions.
It is therefore a primary object of the present invention to provide a new and improved aluminum composite which has sufficient strength to perform the required or desired use thereof and which is considerably less expensive than presently available aluminum alloys, especially aluminum casting alloys.
The instant invention is particularly adapted for use in the manufacture of articles wherein maximum strength for aluminum is not required and wherein slight changes in density would be of no consequence. Some examples of such articles are lawnmower housings, office machine cases and certain small engine parts.
It is also a primary object of the present invention to provide an aluminum composite which exhibits improved properties such as tensile strength, hardness and toughness.
An important object of the present invention is to provide an aluminum composite which may be remelted and cast without any significant loss of its physical or structural properties.
Another object of the present invention is to provide a method for manufacturing an aluminum composite of material in which the physical properties may be varied over a wide range as desired, by appropriate changes in the composition.
Still another object of the present invention is to provide a new and useful aluminum composite which is substantially uniform in construction.
Other objects and advantages of the invention will become more readily apparent from a reading of the specification hereinafter.